Pao OLOGICAL STUDIES OF CONNECTICUT Eeaie 
TOWING, 
GENERAL PHYSIOLOGY OF THE TOBACCO PLANT. 
THE FACTORS OF DEVELOPMENT. 
The interest connected with the tobacco plant is not only of an agri- 
cultural and commercial nature! but is also to a considerable degree 
of a physiological and chemical character. Tirst of all the minuteness 
of the seed strikes us as peculiar when compared with the large plant 
developed in but ninety days rivaling in extent of leaf surface 
most other cultivated plants of equal age. This rapid development 
requires asteady and full nutrition, if the leaves are to become of the 
desired size and quality. In order to accomplish this result the roots 
must be able to grow and extend with corresponding rapidity, requir- 
ing for this purpose not only a loose humus or a fine sandy soil to the 
depth of several feet, but also the presence of all necessary mineral 
nutrients in most easily assimilable form. The soil must, on the one 
hand, admit air freely to the finest rootlets to satisfy the wants of 
respiration and, on the other hand, it must be of such quality as not to 
part with its moisture too easily in a period of dry weather. Thenature 
of the subsoil is also of great importance, since when it is imperme- 
able the stagnant water is just as detrimental to the roots as too great 
loss of water on account of excessive permeability of the soil.’ 
The abnormal physiological condition created by the mutilating 
(topping and suckering) of the plant in order to obtain suitable leaves 
for the requirement of the tobacco manufacturer is also of interest. 
Further points of consideration are the production of the enzyms neces- 
sary for the processes of curing and sweating and, finally, the production 
1'The annual total tobacco production of the globe is estimated by Darmstiidter to 
be nearly 1,000,000,000 kilograms. 
2For full information on tobacco soils see Bulletin No. 11, Division of Soils, 
Tobacco Soils of the United States, 1898, by Milton Whitney. A tropical temperature 
might favor the development of the root in humus soil to such an extent that rela- 
tively less of mineral nutrient for the unit of soil will suffice for a normal plant 
development. The fact that some tobacco soils of Sumatra contain less of nutrients 
than tobacco soils in northern countries and still produce excellent crops is thus 
explained by A. Mayer. 
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